PROJECT SUMMARY: From a cluster of respiratory illnesses in Wuhan, China, to a worldwide pandemic, the world has learned of a novel coronavirus (SARS-CoV-2) but little is known about the pathogenesis that leads to the disease termed ?COVID?. Patients with SARS-CoV-2 infection range from asymptomatic, mild, moderate, to severe infections, resulting in ICU hospitalization and even death. In the US alone, there is a prediction of ~100,000 ? 240,000 deaths from SARS-CoV-2 infections. There is an urgent need to immunophenotype patients with COVID to define biomarkers of disease severity and outcome to inform new interventions to prevent or treat this deadly disease. Key to characterizing the human immune response to SARS-CoV-2, is recruitment , enrollment and retention of a cohort of study participants with COVID. To this end, we will employ best practices in clinical research to pursue three Specific Aims (SAs). In SA1, we will recruit and enroll a well-defined cohort of adults with SARS-CoV-2 (COVID-19); in SA2, we will obtain and store biosamples from patients in this COVID-19 cohort in support the NIAID immunophenotyping effort and in SA3 we will partner with the Clinical & Data Coordinating Center (CDCC) to provide clinical data from this COVID-19 cohort to ensure these samples are highly annotated with key clinical data. Overall, successful pursuit of these SAs will provide well defined clinical samples and high quality clinical data to support the NIAID COVID immunophenotyping effort.